Work has continued on the expression of alu-like genes and their role in the regulation of gene expression. A lot of our previous work has suggested that the expression of alu sequences is significant during development. We have therefore developed several model systems for studying their importance during development. We have employed both the Xenopus laevis and mouse system for this study - using both Xenopus and early mouse embryos and the F9 teratocarcinoma cell - line to study this. In addition, we are studying the role of these sequences in muscle development, a tissue which has shown a considerable level of expression of the alu-binding 63K protein. We have partially purified the protein and the role in the transcription and further expression of alu gene transcription is being pursued vigorously. The Xenopus oocyte which was traditionally used to study the expression of several genes has proved to be a big bonus for the study of the regulation of HIV genes. Work done in collaboration with Steve Josephs in Dr. Gallo's lab has for the first time given concrete proof of translational regulation by the HIV tat gene. In addition, we have been able within this system to demonstrate the presence of a cellular tat like factor which appears important in the expression of HIV genes in this system. The study of this cellular system affords a completely new strategy for interfering with the expression of the AIDS virus. The transactivation of polymerase III genes by both the Bovine papilloma E2 gene and the HIV tat gene is also a likely candidate in the regulation of expression of these viruses. Our continued investigation of the novel area of gene expression will shed some light on the interaction. We have also begun work in collaboration with Dr. Beverly White on the study of several enzymes related to the expression of the fragile X phenotype.